The present invention generally relates to functionalized imprinted materials. More particularly, the present invention relates to amorphous silicas having discrete pores of controlled size and shape with one or more spatially organized functional groups formed therein.
As paragons of substrate specificity and catalytic efficiency, enzymes have been the inspiration behind the design of novel catalytic systems as well as the benchmark against which these systems are judged. In the biological context, novel catalysts generally take two forms. The first category relates to enzyme mutants in which the amino acid sequence of a naturally occurring enzyme has been altered at one or more residue sites to modulate substrate binding, substrate turnover, enzyme stability, or to introduce new functionalities. The second category relates to catalytic antibodies which take advantage of an immune system""s inherent ability to produce antibodies that specifically bind to an antigen. Catalytic ability is introduced into this system by challenging the immune system with an antigen that is also an analog for the transition state of the desired reaction.
Although the procedures for producing the desired mutant enzymes or catalytic antibodies are not always straightforward, they have been generally successful in producing novel enzymes and enzyme-like mimics. However, because of the low substrate concentrations involved (typically micromolar or smaller), the high costs associated with water removal and reactor size make these approaches impractical for many industrial applications.
In contrast, non-biologically based catalysts tend to be much more commercially viable. For example, zeolites are a prototypical example and are generally cost-effective and are robust to a variety of harsh conditions that would denature most proteins. Unfortunately, zeolites, like most inorganic systems, are useful as catalysts for only a limited number of reactions. Because the narrow catalytic range is the main disadvantage to these systems, novel strategies are required for developing more versatile, non-protein based catalysts.
The present invention applies the principles of enzyme specificity and catalysis in a non-biological context. In the most general terms, the present invention relates to amorphous inorganic materials having discrete voids of controlled sized and shape that are akin to enzymatic active sites. The size and shape of the voids are readily varied and are typically complementary to the desired substrate (or the reaction""s transition state). One or more spatially organized functional groups are positioned in a defined three dimensional relationship within each void and with respect to each other such that the imprinted material contains a plurality of substantially similar functionalized void spaces. By varying both the positions and identities of the one or more functional groups, diverse sets of substrate specific adsorbents and non-biologically-based catalysts are created.